system and desktop VFS merged
elanthis at awemud.net
Thu Mar 31 02:34:32 EEST 2005
Diego Calleja wrote:
>El Tue, 29 Mar 2005 23:03:19 -0800 (PST),
>Rahul Sundaram <rahulsundaram at yahoo.co.in> escribió:
>>Freedesktops are not Linux specific while FUSE is.
>I already told that. OSs who don't implement themselves userspace filesytems
>will have to live without them.
>What else could you want to do? Filesystem namespace is something that belongs to the
>operative system level, and it's the operative system who has the power to fix that. Trying
Says who? I say that's absolutely wrong. The only thing that belongs
in the kernel is stuff that requires the kernel. You need the kernel to
do block access. You need the kernel to directly push bits around on
the block device securely.
You don't need the kernel to access CIFS. You don't need the kernel to
access WebDAV. You need the kernel to do the networking, but that's
it. There are many WebDAV implementations that work 100% absolutely
perfectly in userspace. They don't need the kernel.
Neither does D-VFS. It doesn't *need* the kernel for anything. Shoving
craploads of code into the kernel - the absolute last place you want to
add more code - is at its very core a bad idea. If you can possibly
implement something in userspace, then that's where it should be done.
Putting parts of D-VFS into the kernel buys you very, very little. It
can help provide compatibility to old applications. It's hard to
provide that compatibility without the kernel. Possible, sure, but it
can't be done perfectly. And the kernel has stark disadvantages that
I've gone over many times and *not one* of the pro-in-kernel people have
actually addressed those issues, other than saying, "I don't care."
That's not good enough.
The kernel cannot easily be extended with new APIs when new technologies
become available. It does not at all make it easy to securely and
efficiently have bi-directional communication with userspace in response
to in-kernel events like D-VFS would absolutely require for correct user
Compatibility is not a problem. KDE and GNOME have existed for years
with their own VFS systems. FUSE even allows you to wrap those so that
legacy apps get have near-perfect compatibility with those *100%
userspace VFS implementations*.
D-VFS is not and will not be kernel based. If you can't accept that,
you are free to create an in-kernel extensible dynamic user-oriented VFS
system that rocks my socks off and proves me wrong. Let me know when
it's done, since you guys seem to have it all figured out.
>to hide that fact by creating a standard that makes userspace filesystems anything but
>transparent is not going to change that....
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